The inventive concepts described herein relate to a sound detecting circuit, and more particularly, relate to an amplifier circuit for a sound detecting circuit.
A sound detecting circuit may be used to detect a sound pressure level of a sound signal. The sound detecting circuit may include a capacitor-type microphone. The sound detecting circuit may be installed at various electronic devices such as a cellular phone, a notebook computer, a smart phone, a tablet PC, and the like to recognize a voice of a user.
As an electronic device having the microphone becomes small-sized, the microphone may also become small-sized. The less capacitance of the capacitor-type microphone, the lower the sensitivity. Thus, an amplifier circuit to amplify a detected sound signal may be required. In this case, since a noise of the detected sound signal affects the performance of the microphone, there may increase demand for an amplifier circuit that is suitable for miniaturization and is capable of removing a noise of the detected sound signal.